Lim x^2 - 8 + 15
x->3 --------------
x - 3
Note that x^2 - 8x + 15 = (x - 5) ( x - 3)
So
lim (x - 5) ( x - 3)
x → 3 ____________ = x - 5 = 3 - 5 = -2
(x - 3 )
thanks